Adding support for UPDI-over-UART programmers

[Paul "LeoNerd" Evans]

There are several easy hacks to talk UPDI over any standard UART
device. These started with some advice from `pyupdi`[1] about how to
just use a 4k7 resistor on the TX line of any USB-UART bridge to turn
the thing into a half-duplex onewire. I now make and sell two separate
products on my Tindie store[2,3] for doing this and I also link to my
Device::AVR::UPDI CPAN module[4] containing another implementation of
this.

I figure now's about the time for avrdude itself to have an
implementation too, so the standard AVR code-uploading tool can do it.

I'm imagining for example:

  $ avrdude -c updi-uart -P /dev/ttyUSB0 -p attiny814 ...

Would anyone like to have a go at this, based on these two examples? Or
failing that, give me a hand-hold at how to add new programmer support
so I can do it?

Thanks,


[1]: https://github.com/mraardvark/pyupdi
[2]: https://www.tindie.com/products/leonerd/avr-updi-programming-cable/
[3]: https://www.tindie.com/products/leonerd/avr-updi-programmer-with-12v/
[4]: https://metacpan.org/pod/release/PEVANS/Device-AVR-UPDI-0.03/bin/avr-updi

-- 
Paul "LeoNerd" Evans

address@hidden      |  https://metacpan.org/author/PEVANS
http://www.leonerd.org.uk/  |  https://www.tindie.com/stores/leonerd/

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